By far the most common product in the rental shirt industrial laundry market is a four and one-half oz. 65/35 polyester/cotton woven poplin work shirt. This product, in the early 1960s, replaced the 100% woven cotton garments that were the standard in the industry at that time. Attempts have been made to introduce other products into the industrial laundry retail shirt market in the 1980s, but they have either been completely or mostly unsuccessful. While a 80/20 polyester/cotton woven poplin fabric shirt is still being sold, it has poor comfort properties, and is not a significant factor in the market place. Also, attempts were made to market a plaited work shirt with a 100% polyester face and 50/50 polyester/cotton back. However this product was rejected by the industrial laundry rental circuit marketplace for several reasons, including because it was too hot for employees wearing the garment.
Knit shirts are also sold today by rental companies primarily through direct sale. The manufacturers of such shirts, however, do not recommend that the shirts be laundered commercially because of substantial color loss, surface abrasion, and shrinkage. Under industrial laundry conditions, such knit fabrics exhibit significant color loss, excessive shrinkage, abrasion, and pilling, and general breakdown in fabric appearance. Their life expectancy is only half of that of the standard 65/35 polyester/cotton woven poplin shirts, while being 15 to 25% more expensive.
According to the present invention, a knitted fabric has been developed, from which competitive knit garments can be produced which withstand industrial laundering, having a life that compares favorably to the standard 65/35 polyester/cotton woven poplin garment while having good comfort, porosity, and hand properties. The term "industrial laundering" as used in the specification and claims, and as commonly used in the industry, refers to both commercial and hospital industrial laundries, which utilize typical wash temperatures of 145.degree.-165.degree. F., and strong detergent/formulas, which include chlorine bleach, and highly alkaline chemicals. These conditions cause conventional knit fabrics to exhibit significant color loss, excessive shrinkage, excessive abrasion and pilling, and general breakdown in fabric appearance so that they have a life expectancy of much less than 50 industrial laundering wash-dry-wear cycles, making them commercially unacceptable.
According to the present invention a knit fabric suitable for making a work shirt for the rental shirt market that is capable of industrial laundering, having a life expectancy of at least 50 industrial laundering wash-dry-wear cycles, is provided. The two primary aspects of the present invention that result in a knitted product capable of industrial laundering while still having acceptable colorfastness, shrinkage, abrasion, pilling, and general fabric appearance qualities, are the use of air jet spun intimate polyester/cotton blend yarns (e.g. about a 50/50 polyester/cotton blend), and vat dyeing the air jet spun yarn with a vat dye, to impart colorfastness to the cotton component thereof: and dyeing the polyester component as well as with disperse dyes. Also important to obtaining a desired shrinkage resistance, as well as to impart other desirable features (such as soil release and wrinkle reduction features), are practicing the knitting to produce tightly formed stitches, scouring the knit fabric, and finishing the fabric.
According to the invention it is also possible to make a fabric, and a garment produced by the fabric, having a softer hand than the fabric/garment previously described. Soft hand is obtained by first adding a cationic softener to the scoured cloth while still in the jet machine that is used to scour the cloth, and then finishing the fabric in a pass (typically a single pass) using a formula that (in addition to imparting the soil release and wrinkle reduction features described above) assists in imparting soft hand and reduced possibility of needle cutting during the garment sewing process. The formula may include about 35-45% by weight of a glyoxal-based resin, about 15-25% by weight of amphoteric softener, about 3-10% by weight hydrophilic silicone softener, about 1-3% by weight sewing lubricant, about 3-10% by weight of a non-ionic fluorochemical stain release agent, with the remaining approximately 20-25% water.
According to one aspect of the present invention a method of producing a fabric suitable for use as a rental shirt capable of being industrially laundered is provided. The method comprises the steps of substantially sequentially: (a) Air jet spinning an air jet spun intimate polyester/cotton blend yarn, having wrapper fibers holding the yarn bundle together. (b) Vat dyeing the cotton component of the air .jet spun yarn with vat dye and, also dyeing the polyester component with disperse dyes. (c) Knitting the dyed yarn into a fabric suitable for use in the production of a rental shirt capable of being industrially laundered. (d) Scouring the knit fabric, and softening the fabric immediately after scouring; and (e) finishing the fabric to impart soil release, wrinkle reduction, soft hand, and shrinkage resistance properties to the fabric.
Step (c) is practiced to knit the fabric with tightly formed stitches. The designation "tightly formed stitches" in the knitting art has a specific meaning, although the meaning varies numerically depending upon the particular knitting construction utilized. Anything tighter than 35 stitches per inch on jersey fabrics and 38 stitches per inch on pique constructions is considered "tightly formed stitches". Other types of knitting have different numerical values.
The method steps (a) through (e) according to the present invention are practiced to produce a fabric which shrinks a maximum of about 8% both in length and width unrestored after five wash and tumble dry sequences per AATCC Test Method 135, has a colorfastness rating of 4.0 or higher when subjected to AATCC Test Method 61-IIA, has a rating of 4.0 or higher when tested for pilling using ASTMD3512 Resistance to Pilling, Random Tumble test method, a life expectancy of at least 50 industrial laundering wash-dry-wear cycles, and a softer hand than if steps (d) and (e) were not practiced.
Step (a) is typically practiced to produce a substantially 50--50 intimate polyester/cotton blend air jet spun yarn. Step (e) is typically practiced in a single pass using a finish formula containing a glyoxal-based resin, an amphoteric softener, an hydrophilic silicone softener, a sewing lubricant, and a non-ionic fluorochemical stain release agent. There is also typically the further step, between steps (a) and (b), of winding the undyed yarn onto a dye package. The dyes typically used to dye the cotton component are vat black 16, vat brown 1, vat green 1, vat green 3, vat red 13, vat yellow 2, or vat blue 55 dye. Step (b) is typically also further practiced using disperse dyes at the same time as vat dyeing takes place, or in a different dyeing process, the disperse dyes dyeing the polyester component of the intimate polyester/cotton blend air jet spun yarn.
The invention also relates to making a garment capable of being industrially laundered, with the knitted fabric produced by the steps set forth above (typically after scouring and finishing). The garment has a life expectancy of at least 50 industrial laundering wash-dry-wear cycles, and soft hand.
The invention also relates to a knit fabric and garment made therefrom. The knit fabric according to the invention is formed of air spun yarn knit with tightly formed stitches, and is capable of being industrially laundered. The garment shrinks a maximum of about 8% both in length and width unrestored after five wash and tumble dry sequences, has a colorfastness rating of 4.0 or higher when subjected to AATCC Test Method 61-IIA, has a rating of 4.0 or higher when tested for pilling using ASTMD3512 Resistance to Pilling, Random Tumble test method, a soft hand, and has a life expectancy of at least 50 industrial laundering wash-dry-wear cycles. The garment typically comprises a shirt, and the air jet spun yarn is typically an approximately 50-50 polyester-cotton intimate blend having a pique or a jersey knit construction.
It is the primary object of the present invention to produce a fabric for use in making a work shirt, or like garment, capable of being industrially laundered, yet having a knit construction, with good comfort, soft hand, colorfastness, and shrinkage resistance properties. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.